FIGURE 5.

TβRIII associates with lipid raft domains. A, TβRIII constructs were overexpressed in COS7 cells, and TβRIII was immunoprecipitated (IP) and then blotted for endogenous clathrin and flotillin in the immunoprecipitates. B, HepG2 cells endogenously expressing TβRIII or COS7 cells adenovirally infected with either TβRIII-FL or TβRIIIΔgag were lysed and subjected to sucrose density fractionation. Fractions were analyzed by Western blot with antibodies to markers of the lipid-raft pathway, caveolin-1, flotillin-1, and the cholera toxin (CT) B subunit, to confirm lipid raft fractions and an antibody for clathrin-mediated endocytosis, clathrin-heavy chain. Results are representative of two independent experiments; asterisks (^*) represent visible lipid raft fractions.